In vein authentication, an appropriate vein image is easily obtained by stabilizing the posture of a region of a living body with a guide. Recently, a vein authentication function is installed in a portable device, but the use of the device along with the guide loses portability. It is therefore hoped that the authentication is carried out by a movement that naturally holds the region of the living body over the portable device. However, it is difficult to stabilize a position of the region of the living body against a sensor, and hence a photographing range and a photographing point vary for each photographing. For this reason, it is considered that a vein pattern of the whole regions of the living body is enrolled, a part of the whole regions is photographed at the time of comparison and the comparison (partial authentication) of the part of the whole regions is performed (see Japanese Laid-open Patent Publication No. 2012-234440).